A retrospective, postmarketing study demonstrated that voxelotor improved hemoglobin levels and hemolytic markers with a safety profile consistent with the phase 3 trial among patients with sickle cell disease (SCD), according to results from the RETRO study presented at the 62nd Annual Scientific Meeting of the British Society for Haematology.

Voxelotor is approved for the treatment of patients age 12 or older with SCD based on the results of the phase 3 HOPE trial. The trial demonstrated that voxelotor, an HbS polymerization inhibitor, increased hemoglobin levels and reduced markers of hemolysis.

“RETRO is the first multicenter, retrospective study to examine the real-world effectiveness of voxelotor,” the authors wrote. This analysis of the postmarking RETRO study included 140 patients with a mean age of 33 years. In the cohort, 56% of patients were female and 87% had the HbSS genotype.

Continue Reading

The majority of patients were prescribed an initial dose of 1500 mg, most commonly for  reducing their anemia, pain, and the frequency of vaso-oclusive crises. The mean duration of voxelotor treatment was 53.2 weeks.

Voxelotor resulted in a mean peak increase in hemoglobin of 1.5 g/dL from baseline, with 60% of patients exhibiting a clinical response within 12 months of treatment.

Hemolytic markers were also improved with voxelotor treatment, with a mean decrease of 3.4% in reticulocytes compared with baseline and a mean decrease of 1.3 mg/dL compared to baseline for indirect bilirubin.

Treatment-emergent adverse events (TRAEs) that were not related to SCD were similar to those observed in the HOPE trial, including diarrhea, headache, and rash. The majority of TRAEs were mild in severity.

The authors concluded that “this study shows that voxelotor treatment is associated with increased hemoglobin levels and decreased hemolytic markers.”

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


Andemariam B, Osunkwo I, Idowu M, et al. Real-world experience of patients with sickle cell disease treated with voxelotor: a multicenter, retrospective study. Presented at the 62nd Annual British Society of Haematology; April 3-5, 2022. Abstract PO89.